Cook vegetables.
Skin satoimo, and cut in two if large. Skin kabu, and cut lengthwise into two or four.

Bring dashi or water to boil, add usukuchi soy sauce and sake, and cook satoimo on medium low to low heat until almost soft, about 10-15 minutes.

Shake pot occasionally to prevent satoimo from sticking to bottom.

Add kabu and cook for a few minutes.
Remove from heat, and set aside.

2.

Grate daikon, and set aside.

3.

Deep-fry ling cod.
Heat oil on medium high to high heat. When very fine bubbles briskly come up from tips of chopsticks when dipped in oil, oil is ready. The temperature should be quite high.

Coat each fillet with potato starch, shake off excess starch, and slide into oil.

When almost done, raise heat slightly, and hold each fillet to be removed with one end still immersed in oil. This draws out oil and returns it to the pot.
Lift from oil, lightly shake, and place in a drain pan lined with paper towel.

4.

In a medium-size shallow pan, put all ingredients for broth -- dashi, soy sauce, sake and mirin -- and bring to boil.

Put satoimo and kabu (and kabu leaves in photo) in remaining broth, cook 1-2 minutes, and serve in the same bowl.

<Notes>

Any fish works (red-fleshed fish is usually not used).

Vegetables (satoimo and kabu) are optional, but it is always nice to have a different texture and additional taste. Firm vegetables should be cooked (boiled, microwaved, steamed) ahead of time, but leafy greens can simply be added to broth at the very end.

Satoimo and kabu are cooked in dashi for extra (although subtle) flavor. Sake and usukuchi soy sauce are added for the same reason. The vegetables can simply be boiled in water, as the broth of this recipe is quite strong, and the difference in flavor would be very minor, especially if these vegetables are cooked in the broth a little bit longer (another minute).

Because of the strong broth, do not keep the fish in broth for a long time. (Cooling and heating up would make the fish and other ingredients really salty.) You could finish up to Process 3, and continue from Process 4 before serving/eating.